446 



NA TURE 



[September 6, 1894 



of the clearest results of education and experience, 

 containing nothing in common with true instinctive 

 actions. Thus we read on p. 21: — "That the Kea- 

 bird of New Zealand has learned to dig the kidney-fat 

 out of living sheep since the introduction of sheep into 

 that country, is another wonderful instance of change 

 of instinct hardly to be accounted for by means of 

 natural selection, but rather as the result of intelligent 

 experience." 



Speaking of instinct, he maintains " this seems to be a 

 well-defined case of the inheritance of acquired charac- 

 ters. We cannot deny that the idea or knowledge has 

 been acquired, neither can we deny that it has been in- 

 herited." And yet many instinctive actions of the greatest 

 complexity and interest take place under conditions 

 which preclude the possibility of the acquisition of any 

 idea or knowledge. Thus many insects before pupa- 

 tion take the most elaborate precautions, which tend to 

 prevent their detection by enemies they have never seen 

 and never will see in the helpless stage they are about to 

 enter. If knowledge cannot have had any part in the 

 origin of such marvellous instincts, it is unnecessary to 

 suppose that it is an element in the rise of any truly 

 instinctive action. 



In considering the source of organic energy in chapter 

 ii., the author supposes that by the law of conservation 

 of energy all the forces of the environment which act 

 upon an organism must be transferred into some form of 

 energy within it, accounting for " all changes in shape 

 and all changes in the method of activity." In order to 

 help to understand how this may occur, he instances a 

 number of photochemical changes taking place in 

 inorganic bodies. But the law of conservation of energy 

 demands nothing of the kind. The forces which fall upon 

 the organi sm must indeed persist, but not necessarily in 

 any form which can be made use of by the organism ; or 

 they may, and indeed frequently do, serve to expend 

 part of the store of potential energy derived by the 

 organism from other forces. Thus the effect of any ex- 

 ternal force U.j;. light, heat, sound, &c.) upon a peri- 

 pheral end organ is only conveyed to the brain by the 

 expenditure of potential energy derived from food. The 

 animal may benefit by the information received, but the 

 transmission itself is a loss, and not again to the store 

 of force at its disposal. 



When, in chapter iii., the author considers in further 

 detail the action of environing forces, many instances 

 are brought forward, in which it is clear that some 

 necessary condition of development, such as food or heat, 

 is interpreted as a cause of development. It is surprising 

 that the author did not think of applying hii conclusion 

 thai "food is one of the stimulating forces which 

 guide and determine the developmental reactions of the 

 organism " to the vegetable world ; where an endless 

 variety of forms depend upon a food supply which is, 

 when compared with that of animals, rem.irkably 

 uniform. 



The naive manner in which conclusions are drawn is 

 surprising in an author who is evidently a trained 

 biologist, and is accustomed to the indirect and ex- 

 cessively complex relation of causes to effects met with in 

 organic nature. Thus, on p. 47 we are told that 

 "pigment increases in quantity or brilliancy as we 

 NO. I -97. VOL. 50] 



approach the equator, where the light is most intense. 

 There is thus a direct ratio between the amount of light 

 and amount of pigment " ; and again on p. 4.9 : " The 

 plain facts lead to the conclusion that pigment is caused 

 by light acting upon the tissues, and where there is no 

 light there can be no pigment." It is interesting to 

 compare these bald statements with the evidence 

 produced by Dr. A. R. Wallace, that there is no pro- 

 portionate increase in quantity or brilliancy of colour — 

 either animal or vegetable — in tropical as compared with 

 temperate countries ; but that such increase as there is, 

 is merely proportionate to the increase in variety 

 and number of forms of life. ]5u'. apart from this 

 deliberate conviction of one whose opinion on such a 

 subject is entitled to so much cons;deration, the 

 mode of development of pigment in animals is en- 

 tirely opposed to the author's conclusions. The bright 

 colours of insect-imagines are developed in an earlier 

 stage, during which they are comparatively screened 

 from light, and when in the final stage the colours are 

 exposed, they undergo no change in the direction of 

 increasing brilliancy. Even such changes as the darken- 

 ing of the freshly exposed pupal cuticle- long as- 

 sumed to be photochemical— have been shown by the 

 writer to be independent of light, and almost certainly 

 due to oxidation. 



Equally rash and ill-considered is the conclusion, ia 

 the same chapter, that the colours of desert animals and 

 of those living among the sea-weed of the Gulf .Stream 

 are due to a direct photochemical influence of the 

 respective environments, and that the whiteness of Arctic 

 animals "may be primarily due to the small amount of 

 light in those regions." In reaching this last conclusion 

 the author relies upon the supposed fact that <z// classes of 

 animals are similarly coloured, forgetting that when, as 

 in the raven &c., a white appearance is not needed for 

 attack or defence, it is not attained. 



In considering the action of the nervous system, in 

 chapter iv., it is " safely " concluded that " the energy 

 of the forces, acting from without, persists within the 

 living matter as nervous activity and change of nervous 

 condition." It has been already pointed out that such 

 persistence is frecjuently attended by a loss ratlier than a 

 gain to the energy at the command of the organism. 

 The author has thought it worth while to translate long 

 passages from Detmer, and does not appear to be aware 

 that the conclusions he quotes have been refuted l>\ 

 Weismann, and are even rejected by botanists who do not 

 agree with the views of the latter. 



In chapter v. it is contended that development has been ' 

 dependent on association and repetition. It is forgotten 

 that many essential actions are performed but once in 

 the life of the individual {e.g. cocoon-spinning), or are as' 

 perfectly performed the first time as on subsequem 

 occasions {e.g. web-spinning of spiders, sucking of 

 mammals). The author freely admits that such a theory 

 of development demands the transmission of acciuired 

 characters, and it is therefore remarkable that his 

 discussion in chapter vii. of this question — the foundation 

 of every conclusion he brings forward— should be sc 

 brief, and his reasons for accepting such transmission >- 

 unconvincing. 



In chapter ix. the author attempts to illustrate in the 



